1. Field of the Invention
The present invention relates generally to expandable baffle products for sealing the cavities of automobiles and other articles of manufacture and, more particularly, to a baffle apparatus including a piece of heat activated sealing material and a support element on which the sealing material is supported before, during and after activation of the sealing material.
2. Discussion of the Prior Art
During the fabrication of automobiles, trucks and similar over-the-road vehicles, many body components present cavities which require sealing to prevent ingress of moisture and contaminants which can cause corrosion of the body parts. This is especially true with respect to unibody structures in which a heavy frame is replaced with a structurally designed space frame that inherently presents a number of moisture and contaminant collecting cavities. These cavities also serve as passages which attenuate noise and other sounds transmitted through the cavities during normal use of the vehicle.
For example, the upright post structure of a vehicle's body defining a portion of a respective window opening presents an elongated passage or cavity which can collect moisture and contaminants and also transmit annoying sounds unless the passage or cavity is at least partially filled with a sealant material that blocks entrance of moisture and debris, and that also serves as a baffle for muting sounds that would otherwise be transmitted along the length of the passage or cavity. There are other irregular cavities in a vehicle body which desirably are sealed to prevent moisture, noise and contaminants from entering that area and being conveyed to other parts of the interior of the vehicle body.
Many attempts have been made to seal these cavities, including spraying of a sealant into the cavity, introduction of foam products into such cavities, and use of fiberglass matting and the like. These past efforts have not been entirely satisfactory because of the inefficiency of the sealing and baffling methods, the relatively high cost of the sealing process, and the fact that erratic sealing has resulted in many instances.
Foaming in-place has not been totally satisfactory because of the difficulty in controlling where the foam travels upon introduction of the foam into a vehicle body cavity or the like, and the fact that more foam than is actually needed is usually introduced into the body cavity to provide some degree of redundancy in preventing entry of moisture into the cavity during use of the vehicle. Furthermore, foams have a finite life insofar as flexibility is concerned before becoming rigid, thus limiting the time available during which the foam may be introduced into the vehicle cavity. In addition, if the interior surface of the cavity had a somewhat oily surface, the foams would not adequately adhere to that surface and provide an effective seal.
Other types of foam or foamable products are tacky in nature and thus cannot readily be positioned at the exact required disposition in the selected cavity. Such products also present unique packaging problems to the manufacturer, and require special handling during installation.
Certain sealant and baffling materials also are sensitive to the elevated temperature conditions to which a vehicle body may be subjected during fabrication of a vehicle thus causing disruption of the sealant and sound attenuating properties of the sealant. For example, when an automobile body is baked, it is placed in an oven and exposed to an elevated temperature, e.g. 177.degree. C. (350.degree. F.), for a period of approximately 30-45 minutes. As the temperature of the baffling material increases, the material softens and sags, deforming to a point at which it no longer is able to expand to fill the cavity.
It is known to support foamable products by sandwiching foamable material between a pair of spaced parallel sheets of aluminum or the like that are then fastened within the cavity, or to provide a shelf in the cavity to which a foamable product may be fastened. Yet another known construction includes a support element having a circumferential edge on which foamable material may be adhered so that expansion of the foam is directed radially outward by the support element. However, such conventional systems for supporting foamable baffles within a cavity restrict the flow of sealing material in one direction or another during expansion of the material, and add weight, complexity and cost to the apparatus.